I'm running a campaign where the players were told to make 20 level 1 characters each, because they were living in a city that was getting overrun. They got to play one or two characters at a time in a series of super tough scenarios, and the survivors went into a pool that they got to pick their actual player character from.
It's my first time killing off player characters, but everyone's been pretty chill.
And then there's Marcus.

@Norgrath: Haha, I completely understand! It is most certainly not a concept that works for everyone. The goal was to tell a story that made the final team of normally backstabbing drow to bond, and to give us a crash course in DnD 5e at the same time - it worked like a charm. And everyone at the table are in agreement that it's been healthy to try such a high casualty game, which is great :)

@screamingViking: It is! At the moment there are 25 player survivors left, and 10 npcs (7 of which are children), divided on two teams, making their way from the fallen city through the Underdark. The half of the group that went by boat managed to reach the theoretical safe harbor of a kuo-toa city last session, so we'll see how the land group that couldn't fit on the boat will do this weekend!

@Ruth: Haha, Bianka is currently a 7 months old golden retriever and is our ever present companion throughout this adventure. She's gotten used to cries of "NOOOOOOO" and dice flying off the table... and demands pets at regular intervals, as well she should.